1. Field of the Invention
This invention relates to the demulsification of crude petroleum oil.
2. Description of the Prior Art
In the production of crude petroleum oil, the use of a demulsifying agent to separate water from the crude petroleum is often necessary especially where the petroleum producing strata has been acidized by an operation involving forcing corrosion inhibited acid down the oil well and into the petroleum producing strata formation. The acid attacks limestone formations enlarging the fissures and openings through which the oil fluids flow to the well pool, thus increasing the production of oil. Subsequently, the crude petroleum oil is obtained from the well pool in admixture with various amounts of water which form with the crude petroleum oil, in many cases, particularly troublesome emulsions which are often extremely stable and will not resolve on long standing. In addition, as will be understood, water-in-oil emulsions can occur as the result of various operations encountered during the processing of crude or refined petroleum oil.
Polyoxyalkylene compounds are known for use in demulsification of water-in-oil mixtures, for instance, surface active polyoxypropylene esters are disclosed in U.S. Pat. No. 2,950,313 as useful in the separation of water and crude oil mixtures. In addition, polyglycidyl polymers have been suggested as demulsifiers for emulsions of mineral oil such as crude petroleum oil in combination with either soft water or weak brines.
It is known to prepare polyoxyalkylene compounds utilizing tetrahydrofuran in combination with C.sub.2 -C.sub.3 alkylene oxides. For instance, U.S. Pat. No. 3,425,999 relates to the preparation of polyether polyols prepared by reacting ethylene oxide and tetrahydrofuran to produce heteric polyethers and in the Journal of the American Oil Chemists Society 48, 29, kuwamura et al disclose the preparation of block copolymers of tetrahydrofuran and ethylene oxide for use as surfactants. In U.S. Pat. No. 3,644,567, there is disclosed that block polymers prepared by capping a polytetrahydrofuran polymer with ethylene oxide are useful alkylating and acylating agents. Further, in U.S. Pat. No. 4,038,296, there is disclosed the preparation of tetrahydrofuran based copolymers which are heteric adducts of ethylene oxide or propylene oxide and tetrahydrofuran or block polymers of ethylene oxide or propylene oxide reacted with a mixture of ethylene oxide or propylene oxide and tetrahydrofuran. However, the polyoxyalkylene compounds of the invention and their use as crude petroleum oil demulsifiers are neither disclosed nor suggested in the prior art.